The ALEX17 diurnal cycles in complex terrain benchmark

J Sanz Rodrigo,H Owen,E Tromeur,D Cavar,R Li,R Chávez Arroyo,M Avila,O Lehmkuhl,P Santos

doi:10.1088/1742-6596/1934/1/012002

Abstract

The NEWA ALEX17 experiment was conducted with the objective of characterizing the wind conditions upstream of the Alaiz Test Site for the validation of flow models. From the intensive operational period, a case study has been selected for a Wakebench benchmark consisting of four consecutive days with relatively persistent winds from the North. The validation is centered around a 118-m mast at the Alaiz site and six additional masts located along the valley and at the lee side of a ridge delimiting a 8-km long area of interest. The benchmark is a follow-up of the GABLS3 diurnal cycle benchmark in flat terrain to test mesoscale-to-microscale transient and steady-state modeling methodologies in the assessment of stability-dependent bin-averaged wind conditions. Meso-micro methodologies reduce the wind speed mean bias from 32%, at 3-km mesoscale, to ±5%. Beyond mean bias mitigation, these initial results demonstrate the added value of meso-micro coupling at reproducing non conventional wind conditions at the test site like high-shear low-level jets in stable conditions and negative wind shear in unstable conditions. The benchmark also discusses the challenges of each meso-micro methodology going forward.

Highlights

The ALEX17 benchmark is a follow-up of the GABLS3 diurnal cycle benchmark in flat terrain [1] to test mesoscale-to-microscale methodologies in complex terrain
This paper presents initial results of the ALEX17 benchmark focusing on the assessment of wind speed predictions
Initial results of the ALEX17 Diurnal Cycles benchmark are presented on the testing of mesoscale-to-microscale flow models dealing with a 4-day period of sustained northerly winds in the complex topography of the Alaiz test site

Summary

Introduction

The ALEX17 benchmark is a follow-up of the GABLS3 diurnal cycle benchmark in flat terrain [1] to test mesoscale-to-microscale methodologies in complex terrain. The benchmark is a follow-up of the GABLS3 diurnal cycle benchmark in flat terrain to test mesoscale-to-microscale transient and steady-state modeling methodologies in the assessment of stability-dependent bin-averaged wind conditions. Meso-micro methodologies reduce the wind speed mean bias from 32%, at 3-km mesoscale, to ±5%.

Results

Conclusion